Oil arrives at the oil burner unit at various viscosity levels as a result of variations in the storage area temperature, variations within the oil itself and variation in temperature caused by the temperature of the oil when delivered.
As a consequence, it has been necessary to size the jet orifice of oil burner units to accommodate fuel oil the viscosity of which may be higher than what may be termed normal or desirable. While this ensures that the oil burner will function with fuel oil the viscosity of which is above normal or desirable, it results in increased fuel consumption per unit of time.
It has, of course, been recognized that if the storage tank for fuel oil is outside the building and above ground, provision should be made to heat it to ensure operation of the oil burner. It has also been recognized that there are advantages in vaporizing fuel oil but, as far as we are aware, there is no available system for controlling the temperature of No. 2 fuel oil either in terms of viscosity or of its vaporization that meets structural and functional requirements.